1. Field of the Invention
The present invention relates to a process for the production of polyhydroxystyrene (PHS) directly from a substituted phenyl carbinol ("carbinol") such as 4-hydroxymethylcarbinol (HPMC) and which PHS has a novolak type structure which has utility in the electronic chemicals market such as photoresist compositions.
2. Description of the Prior Art
In the past, one of the ways of preparing polyhydroxystyrene (PHS) was the use of 4-hydroxystyrene (HSM) as the starting material; note European Patent Application No. 0-108-624. 4-Hydroxystyrene is a well-known compound in the art.
Although there are several known ways to prepare 4-hydroxystyrene, these known methods are not commercially feasible in the further utilization of the 4-hydroxystyrene. The 4-hydroxystyrene itself is difficult to isolate since it (1) readily decomposes, and (2) is toxic via skin absorption and, as a result, those skilled in the art have made numerous attempts at finding a method of synthesizing PHS in a manner which avoids using the 4-hydroxystyrene as the starting material.
The following prior art references are disclosed in accordance with the terms of 37 CFR 1.56, 1.97, and 1.93.
U.S. Pat. No. 5,087,772 (issued Feb. 11, 1992) discloses the preparation of HSM by reacting 4-acetoxystyrene (ASM) with a suitable alcohol in the presence of a catalytic amount of a suitable base.
U.S. Pat. No. 5,340,687 discloses the alkylation of a linear polyhydroxystyrene.
European Patent Application No. 0-128-984 (publication no.) filed Aug. 30, 1983 discloses a process for the production of para-vinyl phenol (HSM) by dehydrogenation of para-ethyl phenol.
European Patent Application No. 0-108-624 (publication no.) filed Nov. 4, 1983, discloses a process for the production of p-vinyl phenol polymer (polyhydroxystyrene polymer--PHS) by polymerizing p-vinyl (HSM) in the presence of water and iron.
U.S. Pat. No. 4,032,513 (issued Jun. 28, 1977) discloses a process of producing PHS by cationically polymerizing HSM in the presence of a nitrile such as CH.sub.3 CN using a cationic polymerization initiator in a homogeneous reaction system.
Other prior art references which relate to the present invention include U.S. Pat. Nos. 2,276,138; 3,547,858, 4,544,704; 4,678,843; 4,689,371; 4,822,862; 4,857,601; 4,868,256; 4,877,843; 4,898,916; 4,912,173; 4,962,147; and 4,965,400.
All of the above-cited prior art and any other references mentioned herein are incorporated herein by reference in their entirety.